Mushroom Used in Traditional Chinese Medicine Causes Weight Loss

Traditional Chinese Medicine has a long history in Asian countries dating back thousands of years. One class of traditional remedies commonly in use consists of medicinal mushrooms such as Ophiocordyceps sinensis, Antrodia cinnamomea and Agaricus blazei Murrill, which contain a wide range of immuno-modulatory and bioactive compounds. One of the most intriguing medicinal mushrooms is the Basidiomycete fungus Ganoderma lucidum, which has been used for centuries to promote health and longevity. Previous studies have shown that triterpenes and polysaccharides isolated from G. lucidum inhibit adipocyte differentiation and produce hypoglycaemia effects in diabetic mice. In addition, proteoglycans isolated from G. lucidum fruiting bodies induce antidiabetic, antihyperlipidemic and antioxidant activities. However, it remained unknown whether G. lucidum produces any effect on body weight and obesity-related disorders.

A recent study indicates that changes in the composition of the gut microbiota are associated with the development of obesity and its associated metabolic disorders. The gut microbiota comprises trillions of bacteria that contribute to nutrient acquisition and energy regulation. An increased ratio of the major phyla Firmicutes/Bacteroidetes and changes in several bacterial species can promote the development of obesity in both dietary and genetic models of obesity in mice. Other studies in obese animals suggest that obesity-induced gut dysbiosis caused by either environmental or genetic factors impairs intestinal integrity. This process leads to the release of the endotoxin lipopolysaccaride (LPS) from intestinal Gram-negative bacteria into the bloodstream, in turn, leading to metabolic inflammation and insulin resistance in obese mice due to stimulation of Toll-like receptor 4 (TLR4)-mediated inflammation. Moreover, chronic injection of LPS in mice leads to mild obesity and insulin resistance, highlighting a possible role for microbiota-derived LPS in obesity-induced inflammation.

A number of treatments, including antibiotics and prebiotics, are being evaluated for the management of obesity and its related metabolic disorders. For example, antibiotic treatment alters the gut microbiota, reduces blood endotoxemia and improves glucose tolerance in mice lacking the leptin gene (ob/ob mice) or in mice fed with a HFD19. In addition, prebiotics are non-digestible, fermentable carbohydrates and fibres, which reduce body weight and exert anti-inflammatory effects mainly by enhancing the growth of specific beneficial bacteria found in the gut. Prebiotics not only alter the intestinal microbiota but also improve intestinal tight junction integrity and decrease blood endotoxemia caused by LPS18. Prebiotics may, therefore, protect animals against obesity-induced inflammation.

Taiwanese researchers have shown that a water extract of Ganoderma lucidum mycelium (WEGL) reduces body weight, inflammation and insulin resistance in mice fed a high-fat diet (HFD). Their results indicate that WEGL not only reverses HFD-induced gut dysbiosis—as indicated by the decreased Firmicutes-to-Bacteroidetes ratios and endotoxin-bearing Proteobacteria levels—but also maintains intestinal barrier integrity and reduces metabolic endotoxemia. The anti-obesity and microbiota-modulating effects are transmissible via horizontal faeces transfer from WEGL-treated mice to HFD-fed mice. They further showed that high molecular weight polysaccharides (>300 kDa) isolated from the WEGL extract produce similar anti-obesity and microbiota-modulating effects. They concluded that, "Our results indicate that G. lucidum and its high molecular weight polysaccharides may be used as prebiotic agents to prevent gut dysbiosis and obesity-related metabolic disorders in obese individuals."